I have an Autometer Carbon Fiber Boost Gauge. A few weeks ago the needle fell off. So I sent it back to the company I got a new one. I just received the new gauge and swapped the new one but kept all existing hardware, wiring and vacuum line as the previous.

The new gauge reads different than the previous gauge. More Vacuum, less boost. I just figure that these gauges aren't accurate.

The only change I did was put a Borla Cat-back on. I wouldn't think that would change anything.